The present invention is not to be limited to use in breast implants. However, as a manner of convenience and to explain some of the types of problems that the present invention addresses, problems associated with compositions for breast implants are discussed. Millions of women have undergone breast augmentation and reconstruction in the past few decades. Most women choose augmentation to enhance the size and shape of one or both breasts for personal or aesthetic reasons. In contrast, women who undergo a reconstruction procedure want to reconstruct a breast that has been removed, typically for health reasons, such as tumor removal. The reconstruction procedure may vary from a modified radical mastectomy (removal of the underlying muscle as well as the breast), to a simple mastectomy (removal of one breast), to a bilateral mastectomy (removal of both breasts) or to a lumpectomy (removal of a portion of the breast). In either augmentation or reconstruction, the modality intimates the surgical implantation of a breast prosthesis (implant).
Several types of implants are known for breast reconstruction or breast augmentation. These implants often contain an envelope or shell with a closed space that can be filled out with a filler composition.
Conventional implants for treating breast augmentation or reconstruction include a shell or envelope that is filled with a filler composition, for example, silicone gel, saline solution, or other suitable filler. It is desirable that the filler have lubricating properties to prevent shell abrasion, remain stable over long periods of time, and have physical properties to prevent skin wrinkling and implant palpability.
While breast implants containing silicone-gel as a filler are widely used for breast augmentation or reconstruction, a variety of potential disadvantages have been recognized with respect to the stabilization of the implants and the immune system. First, the silicone gel-filled implants have a tendency to leak. In 1992, the FDA issued a voluntary moratorium on silicone gel-filled implants due to public health concerns regarding the potential link between leaking silicone gel-filled implants and autoimmune diseases. Young et al., Plast Reconstr Surg. 1996 September; 98(3):552, 554. To date, the long term effect of silicone-gel on the immune system is still unknown. Second, the leaking of the implants necessitates the need for additional surgeries for removal or repair of the implants. Third, the silicone-gel as a filling material has a greater density than saline or natural tissues which may cause recipients back pain. Lastly, the silicone-gel implant does not mimic the touch and feel of a real breast.
Therefore, many plastic surgeons turned to saline as an answer to silicone-gel problems. Several implants which use saline are known and were found to be advantageous over silicone-gel for several reasons. Saline has a lower density than silicone-gel causing less strain on recipients' backs. In addition, if the implant leaks, the saline solution is non-toxic providing a more tolerated and safer implant than those containing silicone-gel.
However, while the saline implant offer significant advantages over the silicone-gel implant, various problems have been encountered. Implants using saline are disadvantageous in that they frequently result in capsular contraction. Pfleiderer et al., Journal of Biomedical Materials Research, Part A 2003; 64A(1):12, 13. Capsular contraction is a phenomenon where the body forms a lining of fibrous tissue encapsulating the breast implant and the resulting capsule tightens and squeezes the implant. Symptoms range from mild firmness and mild discomfort to severe pain, distorted shape, palpability of the implant, and/or movement of the implant. Additional surgery is needed in cases where pain and/or firmness is severe. This surgery ranges from removal of the implant capsule tissue to removal and possibly replacement of the implant itself. There is no guarantee that capsular contracture will not occur after these additional surgeries.
Saline implants may have to be removed and replaced periodically for other reasons—they fracture or they deflate. Saline, because it is less viscous than silicone-gel, settles in the bottom portion of the implant when the recipient is upright. Young & Watson, Clin. Plast. Surg. 2001; 28(3): 451, 460. This leaves the upper portion of the implant prone to excessive folding or wrinkling, causing stress fracturing of the shell at the fold points. Eresk et al. U.S. Pat. No. 5,067,965, col. 1; Young & Watson, Clin. Plast. Surg. 2001; 28(3): 451, 460. Furthermore, the saline-filled implants have a tendency to drain gradually in about ten years. See Fallot, U.S. Pat. No. 6,156,066. Barring any deflation or rupture complications, saline as a filler for breast implants produces an unnatural feel and look to the implant. Fallot, U.S. Pat. No. 6,156,066.
In response to the failures of saline and silicone-gel implants, there have been a number of attempts to make a prosthesis filled with a non-toxic filler that that mimics the shape and feel of a natural breast provided by silicone-gel yet is safe to the immune system like saline. Other attempts to provide a safe filler material include polyethylene glycol (Robinson, U.S. Pat. No. 6,312,466), triglycerides (Destourt, U.S. Pat. No. 4,995,882), and even honey (Bretz, U.S. Pat. No. 5,500,017). However, the triglyceride oil disclosed in Destonet et al. or honey disclosed in Bretz fails to provide an implant that is aesthetically pleasing and also duplicates the touch and feel of a natural breast due to the low viscosity of the fillers. Young & Watson, Clin. Plast. Surg. 2001; 28(3): 451, 480.
Due to the limited options and the inadequacy of current fillers to achieve the desired results, there is a need for the current invention.
Accordingly, it is an object of the present invention to provide an effective composition for filling an implant.
It is yet another object of the present invention to provide a composition and method for filling a prosthesis that allows the composition to transition from a liquid to a gel phase at body temperature.
It is another object of the present invention to provide a composition and method for filling an implant which is gelatinous so as to decreases the risk of ruptures due to implant folding.
It is still another object of the present invention to provide a composition and method for filling a prosthesis which reduces leakage and migration of the filler throughout the body.
Another object of the present invention is to provide a composition for filling a prosthesis that closely approximates the touch and feel of a real breast.
These and other objects, features, and other advantages of the present invention will become apparent after a review of the following detailed description of the disclosed embodiments.